Off-peak power and metering system and apparatus



Aug. 23, 1932. WOQD 1,873,238

OFF-PEAK POWER AND METERING SYSTEM AND APPARATUS Filed Nov. 2, 1929 Yheating,

Patented Aug. 23, 1932 atoms a. woon, or x'xwaunrronr,

mvnmr 001mm, or nssacnusn'rrs IASBACHOOETTB, ASSIGNOB TO THE CHASI-UIWBUBYPOBT, KASSACHUSETTS, A CORPORATION OI OI'I-PIAI rown AID T331110SISTER AND APPARATUS 'Apnucatien fled [member 8, 1988. Serial No.404,491.

This invention relates to electric distribution systems and particularlyto a system for connecting power consuming devices to an electricsupply-circuit at times of low I power consumption or off-peak load onthe supply circuit and for metering the power consumed for such devicesat a lower rate than for the power consumed at other periods.

The usual distribution system has periods, known as off-peak riods, whenthe demand for power is re atively small and when power is usually soldat a lower rate than during other periods. There are certain powerconsuming devices, as, for instance, those for electrically heating andstoring water that are well adapted to be operated at off-peak riodsand, in the case of water (if; hot water can be stored for use at timesother than oil-peak periods.

Since the char s for normal and for offpeak power are ifierent, it isusual to vprovide one meter for measuring the normal power and a secondmeter for measuring the ofi-peak power. This method thus involves theuse of two meters which increases the expense of an installation andalso complicates the bookkeepin system.

It is an ob'ect of t e present invention to meter both t e normal powerand the oil'- peak power with one metering instrument, and to cause themeter automaticall to operate at the off-peak period at a ifl'erent andslower rate which is proportional to the difference in cost between thenormal and the 'ofi-peak power.

A further object of the inventlon is the rovision of means to connectthe ofiak oad with the circuit at the beginning 0 the off-peak periodand at the same time to alter the rate of operation of the meter tocorrespond with the oil-peak charge for power and to disconnect theoff-peak load from the circuit and restore the meter to its normal rateof operation at the end of the elf-peak period. A further object of theinvention is the provision of means responsive to the energization ofthe power circuit to connect the oilpeak load to the circuit during theoil-peak period which means shall be so arranged that the beginning ortermination of the oil-peak period is delayed for so long as the powercircuit remains without energy, thereby providing a full period ofofi-peak power regardless of the failure of power on the supply circuit.

A further object of the invention is generally-to improve upon off-peakmetering and ad supplyin systems.

The fi re is a iagrammatic representation of t e oil-peak metering andload su plying system and apparatus embodying the present invention.

As here shown, the ofi-peak power consuming device is illustrated as ahot water heating and storing apparatus consisting of the storage tank10, the electric heater 12, and the circuit opening and closingthermostat 14 which is adapted to close the circuit through the heatinelement when the water in the tank is cold and to open the circuit whenthe water is hot. The power for operating the heatin device is suppliedby the conductors 16 an 18 of a supply circuit and is metered by theusual type of watt hour meter having e current winding 22 which is inseries with the load and the potential winding 24 which is energized bthe potential of the circuit.

In accor ance with this invention, means are provided to cause the meterto operate at a low rate during the off-peak period, and also to connectthe load consuming device to e power circuit at such time. To this end,a resistance 26 is arranged in series with the potential winding 24.During the normal power period of the sup ly circuit the resistance isshunted out o the circult of the otential coil. During the off-peakperiod,

owever, the shunt is removed and the resistance is included in serieswith the potential coil. Due to the resistance, the meter operates at aslower rate than when the resistance is out of the circuit and thuspermits more power to be drawn from the supply circuit than is recordedby the meter. The value of the resistance is such as to cause the meterto read low b an amount which is proportional to the ifierence betweenthe rates for normal and ofi-peak power. Thus while the customer will bebilled at the rate for normal power, his charge will be less than forthe total ower he has actually used, with the result that the ofi-peakpower costs less than the normal power.

The resistance 26 and also the load dev ce 10 is out into and out ofcircuit at the be nning and end of ofi-peak riod by a time controlledswitch herein iagrammaticall shown as including the switch arm 28 wh1cis pivoted in the middle on a pm 30. Said arm carries at one end amovable bridging member 32 that is arranged to enga e an disengagecontact members 34 and 36 t at are connected to the terminals of theresistance 26, whereby to shunt the resistance into and out of thecircuit of the potential winding 24. A second bridging member 38 iscarrie by the other end of said switch arm and is adapted to engagestationary contact members 40 and 42 which control t e energization ofthe oif-peak load circuit. The contact member 40 is connected through aconductor 44 and through the series winding 22 of the watt hour meterwith the conductor 16 of the supply circuit. The contact member 42 sconnected by a conductor 46 with the stationary contact member 48 of adouble throw switch, the movable member 50 of which is connected by aconductor 52 in series with the thermostatic switch 14 and one terminalof the heating element 12. The other terminal of the heating element isconnected by a conductor 54 to the other conductor 18 of the supplycircuit. Thus, when the bridging member 38 engages its stationarycontact members 40 and 42, the heating element 12 is connected to thesupply circuit, providing the double throw switch is in the positionshown which is the normal position.

If the load 10'is desired to be operated at normal periods, the doublethrow switch is operated to move its movable member 50 into engagementwith the other contact member 56 thereof which serves to connect theconductor 52 of the heating element with the conductor 58 and throughsaid conductor and the conductor 44 with the supply conductor 16,thereby cutting out the time controlled switch.

When the load controlling switch compris ing the bridging member 38 andthe contact members 40 and 52 is closed, the resistance controllingswitch is open, thereby removing the shunt from the resistance and thusincluding it in the circuit of the potential winding 24.

The operating mechanism of the switch includes a cam arm 60 which ispivoted in its middle on the pin 62 and has at its upper end a spring64, the upper end of which is connected with an arm 66 of the switch arm28. The arrangement is such that when the cam arm 60 moves the spring 64from one side to the other of the pivot point 30, the switch is causedto move rapidly in one direction or the other. The 0 ration of theswitch is controlled by timing mechanism 68 which preferably is drivenby a synchronous electric motor which is now common in the art and neednot be further shown and that is connected by the conductors 70 and 72with the conductors 16 and 18 of the power circuit. With this type oftiming mechanism, the power circuit is usually provided with atime-controlled mechanism that maintains a constant average frequency onthe circuit and thus causes the accurate timing of said time controlledmechanism. Said mechanism is provided with a shaft 7 4 that, if thesupply circuit has but one off-peak period in a da rotates once intwenty-four hours. Said shaft is provided with a cam 76 that engages thecam roller 78 the lower end of the cam arm 60 and has a working face 80,the extent of which corres onds with the extent of the ofi-peak perioWith this arrangement,

when the working face 80 is travelling over the cam roller 7 8, the loadcontrolling switch is maintained closed and the resistance controllingswitch is maintained open, thus supplylng off-peak power to the loaddevice and metering of such power at a reduced rate. When the workingportion 80 of the cam passes beyond the roll 78, the spring 82 connectedwith the cam arm moves the switch in the opposite direction and thusopens the circuit or the load device and restores the meter to itsnormal rate of operation.

The synchronous motor that drives the timing mechanism 68 depends forits operation upon the maintenance of energy in the supply circuit andwhen the supply circuit is without power, the timing device does notoperate. Since the cam 76 is adjusted to provide a certain time duringwhich oil-peak power may be taken from the su ply circuit, the failureof power on the supp y circuit does not limit the extent of time duringwhich off-peak power may be used. Consequently, the customer can use thefull period for off-peak power when power is restored to the circuit,regardless of how long the power has been 05, although the oil-peakpower may be taken during the normal period of the circuit. Thisarrangement thus provides a customer with a full extent of service forwhich he has contracted and penalizes the power company for the failureof power.

I claim:

1. An electric power distribution system having a meter having a normalrate of operation for recording the power consumed in the system, a loadcircuit, means governed by the energization of the system for connectingsaid circuit to the system, and means operated upon the connection ofthe load circuit to alter the rate of operation of the meter.

2. The combination of a ower circuit, a

watt hour meter for recor ing the power consumed in the circuit, anofi-peak power consuming device adapted to be connected to the circuitat times of low power demand thereon and time controlled means operativeonly when said power circuit is energized for connecting sa1d loaddevice to the circuit and also for reducin the rate of operation of saidmeter, where y to cause sa1d meter to record a lesser amount of powerthan. is actually used by said load device during its period ofconnection to the system.

3. The combination of a power circuit, a load circuit, and means forsupplying said load circuit with power from sa1d power circuit for apredetermined period of time, said means including a switch forconnecting and disconnectin said circuits and controlling means for sa1dswitch including timing mechanism controlling the opening and closing ofsaid switch and energized from said power circuit'and operative onlywhen said power circuit is ener ized.

4. The com ination of a power circuit, a load circuit, and means forsupplying said load circuitwith power from sa1d power circuit for apredetermined period of time, said means including a switch forconnecting and disconnecting said circuits and controlling means forsaid switch including timing mechanism controlling the opening andclosing of said switch and having means controlled by conditions of saidpower circuit for con trollin the starting and stopping thereof.

5. T e combination of a power-circuit, a load circuit, and means for suplying said load circuit with power from said power circuit for apredetermined period of time, said means comprising a switch forconnecting and disconnecting said circuits and time controlled operatingmechanism for said switch including a synchronous motor driven by saidpower circuit, and means operated by said motor for operatin saidswitch.

In testimony whereo I have signed my name to this specification.

MORRIS B. woon.

